Lawyers for a former California gang leader have asked the state supreme court to block his execution Tuesday, while California Governor Arnold Schwarzenegger considers granting clemency.

Stanley "Tookie" Williams has been convicted of four murders and was the co-founder of the infamous Crips street gang.

His case has attracted international attention because Williams is the author of a series of children's books warning young people about the dangers of gangs.

His lawyers argue that the books are evidence that Williams has turned his life around during his 24 years in prison. Williams has apologized for his gang activity, but denies committing the 1979 murders.

In an earlier appeal, the California high court upheld Williams' conviction.

Mr. Schwarzenegger's decision on clemency is expected Monday. In two other death penalty cases he has refused clemency appeals.